Excess flow valves

ABSTRACT

An excess flow valve (EFV) for installation in a service line of natural gas distribution system serving an existing structure. The EFV has a cylindrical housing having a first length and a second length and a through hole therethrough for passage of gas. The EFV  11  engaged in the through hole of the first length and the second length has an expandable wall which can be expanded and fixed in said service line.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pipeline excess flow valve (EFV) andits retrofitting with compatible installation equipment into an existinggas service line.

2. Prior Art

Conventional combustible gas distribution systems bring gas from astreet main below ground level, through a tapping tee, a service line, ariser above ground level, a meter cock, a regulator, a meter and theninto the customer's structure. An example of such system is shown inFIG. 1.

Rupture of the line or failure of fittings between the consumer propertyline and the served customer structure can occur for any number ofreasons. Among these are digging by the customer or other party,vehicular impact, ground settling, failure of a regulator, failure of ameter, failure of fittings and earthquakes. Rupture of the line orfailure of fittings can also occur on the inside customer fuel gaspiping or flexible connection. Dangerous explosive conditions can arisewhen any such rupture occurs.

Prior art patents show various structures for shutting off the gas flowwhen the flow exceeds a predetermined value, e.g. due to the downstreamrupture. Excess flow valves are used in the natural gas industry toprevent explosive pipeline gases such as natural gas, propane, methane,coal gas, town gas, etc. from escaping when a pipe is ruptured. Thesesafety valves will remain open during normal use, when there isbackpressure downstream from the valve, but will trip (snap shut) whenthe downstream pressure disappears. This prevents fires and explosionswhen gas lines are ruptured.

In operation, the stem of a conventional EFV such as that shown in U.S.Pat. No. 5,551,476 is spring biased opposite to the direction of gasflow. Under normal conditions the poppet on the stem is held away from avalve seat by the bias spring. When the flow is excessive such as whenthe service line ruptures downstream of the EFV, the forces from theflowing fluid overcome the spring bias and the poppet closes against theseat, shutting off the flow. Thus, the dangerous flow of combustible gasis stopped.

Presently, in order to install an EFV in an existing service line a holeor trench must be dug, the service line pressure must be reduced tozero, and the service line must be cut. This is not only expensive, timeconsuming, and disruptive to customers and traffic flows, it is alsoimpractical in terms of the human resources required.

The main technology barriers to retrofitting EFVs without digging havebeen the actual anchoring of the device in the service line. Theanchoring of the device has been an issue since it is unacceptable todamage or otherwise alter the interior wall of the service piping. Themethod of insertion has been an issue because the valves and fittingsattached to the meter set have unpredictable geometry and the bend inthe service riser presents a constraint in terms of the length of theEFV and the rigidity of the installation tool.

OBJECT AND SUMMARY OF THE INVENTION

The object of the present invention is directed to a unique EFV andinstallation equipment engaged to the EFV during its installation whichtogether overcome the deficiencies and problems in the prior artdiscussed above. The compatible EFV and installation equipment providesa new solution for retrofitting EFVs in service lines that involves nodigging, thereby causing far less disruption to the community. Theinstallation is effected from the customer meter set, using ahydraulically expandable element integral with the EFV that anchors theEFV inside the existing service line by the force of an interferencefit.

A primary feature of the engaged EFV and compatible installationequipment provides an external geometry that is initially smaller indiameter than that of the inner diameter of the service line in whichthe EFV is to be installed. This permits passage of the EFV through theservice line and its appurtenances to the point of installation withoutdamage.

When the EFV has been inserted to a predetermined point in the serviceline, it can be expanded to the diameter needed for secure anchoring.The EFV is made of a material that allows for enough expansion to anchorthe EFV without cracking, splitting, or otherwise deforming in anirregular manner. Put simply, this portion of the EFV is blown up like aballoon.

The method for the actual hydraulic expansion is and has been for sometime in the public domain in the form of a method of power plant steamturbine condenser tube sleeving (repair), however the concept for usingthis for anchoring an EFV is entirely new and constitutes a secondarycomponent of this original idea and application.

The installation equipment consists of a hydraulic pump, a flexiblewater line, and a mandrel that slides into the unique hydraulicallyexpandable element of the EFV. The anchoring force, measured by apressure gauge on the installation equipment, is high enough that themandrel can simply be pulled out of the EFV when the expansion cycle isfinished.

Thus, the features of the EFV according to the invention in cooperationwith its installation equipment are intended to permit a user to:

-   -   (1) Retrofit the EFV in the customer's meter piping while the        service line remains pressurized.    -   (2) Insert the EFV through the service line up to the tee that        is attached to the gas main, and    -   (3) Use hydraulic pressure to expand a specific portion of the        EFV so as to contact the inside of the service line and lock the        EFV in place.

Though the device is metal, its design would be such that the metalexpands much like a balloon under the applied pressure. This would havethe further benefit of insuring that no sharp edges are in contact witha plastic service line.

As indicated above, installation equipment consists of a hydraulic pump,a flexible water line and a mandrel that slides into engagement with thehydraulically expandable element of the EFV. The anchoring force,measured by a pressure gauge on the installation equipment, indicateswhen the expandable element has expanded to contact the service line.Thereafter, the mandrel can be withdrawn out of the EFV when theexpansion cycle has ended.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and the nature and advantages of the present inventionwill be more apparent from the following detailed description of anembodiment taken in conjunction with the following drawings, wherein:

FIG. 1 shows a conventional natural gas distribution system;

FIG. 2 shows an elevation view of the EFV according to the inventionbefore its use;

FIG. 3 shows a cross-sectional view along section line 3-3 of FIG. 2;

FIG. 4 shows an elevation view of the mandrel, fluid line and hydraulicpump;

FIG. 5 shows an elevation view of the mandrel and fluid line of FIG. 4inserted into the EFV of FIG. 2 in the service line prior to engagementof the EFV in the service line;

FIG. 6 shows the EFV of FIG. 5 expanded into engagement with the serviceline;

FIG. 7 shows the mandrel and fluid line of FIG. 6 withdrawn from theexpanded EFV of FIG. 6, and

FIG. 8 shows a cross-sectional view along section line 8-8 of FIG. 6with the service line not shown.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

EFV 1 shown in FIG. 2 is intended for installation in an existingconventional natural gas service system such as that shown in FIG. 1 toprevent escaping gas entering the home of a customer from a ruptured gasline downstream from the gas meter. The distribution system of FIG. 1 isshown connected between a tapping tee on a gas main and a gas meterlocated in the home of the customer. The service line shown in thesystem is normally buried after these connections have been made.

Installation of the EFV 1 is accomplished by inserting it through thebypass tee shown in FIG. 1 on the inlet side of the gas meter and fixingit to the inner wall of the gas pipe which extends to the gas main.Insertion under pressure is accomplished by way of a “stuffing box”, aconventional device that consists of a sealed chamber which is attachedto the bypass tee and allows control of a sliding rod or cable (notshown). One end of the rod or cable is outside of the stuffing box,allowing direct control by the operator while the opposite end is sealedinside the pressurized system. The seal is maintained via a gland nutand elastomer that compresses around the rod or cable when the nut istightened. Such a device is well known within the industry andaccordingly not an inventive feature of the claimed invention. Theprogression of drawings from FIG. 2 through FIG. 8 illustrates thestructural components and steps involved in the installation of EFV 1 insuch gas pipes and removal of the installation equipment after theinstallation.

As shown in FIG. 2, EFV 1 has a continuous cylindrical housing 10 madepreferably of metal that has the same outer diameter throughout itslength and a through hole 11 that has inner diameters over selectedlengths of the housing 10 which are different from each other so as tosupport the different functions of housing portions 2, 4 of housing 10discussed below.

Portion 2 extends over a length 6 of cylindrical housing 10 and housesconventional hardware 12 similar to that shown in U.S. Pat. No.5,551,476 to control the opening and closing of an EFV valve therein. Ashardware 12 is not an inventive feature of the present invention, itwill not be addressed further.

Portion 4 extends over a length 8 of cylindrical housing 10 and isintegrally formed as a unit with portion 2. Located within the length 8of portion 4 is a laterally expandable wall 14. The inner diameter 16 ofthrough hole 11 over the length of wall 14 is larger than inner diameter18 located at opposite ends 15, 17 of portion 4. Thus, expandable wall14 is thinner and more flexible than the wall of housing 10 located atopposite ends of portion 4.

FIG. 4 shows the installation equipment 20 which serves to locate andfix EFV 1 at a predetermined position in the service line downstreamfrom the customer's gas meter. This equipment consists of a hydraulicpump 22, flexible fluid line 24, and a mandrel 26 designed for sealedengagement with opposite ends 15, 17 of portion 4.

Mandrel 26 comprises a cylindrical housing 28 a closed first end 30 anda second end 32 having an inlet engaged to an end of fluid line 24. Theother end of fluid line 24 is engaged to hydraulic pump 22.

Housing 26 is closed with the exception of fluid outlet hole 34 and theinlet in its second end 32. Finally, elastic O-rings 36 are fixed tohousing 26 near opposite ends 30, 32 so as to be spaced apartsubstantially the same distance as opposite ends 15, 17 of portion 4 ofEFV 1.

Retrofitting EFV 1 into an existing gas service line begins withinserting mandrel 26 into EFV 1 as shown in FIG. 5 so that O-rings 36are respectively engaged to opposite ends 15, 17 of portion 4 to sealmandrel 26 in portion 4. This engagement creates an annular sealed space37 and confined between mandrel 26 expandable wall 14. After mandrel 26is engaged in EFV 1, they can be easily inserted into service line 38 asshown in FIG. 5 since the outer diameter of the engaged EFV 1 andmandrel 26 are smaller than that of the inner diameter of service line38. The engaged EFV 1 and mandrel 26 can then be moved to apredetermined position in service line 38 by manipulation of flexiblefluid line 24.

After the engaged EFV 1 and mandrel 26 have reached the selectedposition in service line 38, an operator can initiate operation ofhydraulic pump 22 to force fluid through fluid line 24 into mandrel 26and out fluid outlet hole 34 into sealed space 37. The pressure createdby the influx of fluid into sealed and confined space 37 results in thelateral expansion of expandable wall 14 into fixed engagement with theinner wall of service line 38 as shown in FIG. 6.

FIGS. 3 and 8 respectively show cross-sections of annular expandablewall 14 before and after its expansion by the fluid pressure created byhydraulic pump 22 in annular space 37.

After the operator is satisfied that EFV 1 has been successfully fixedin service line 38 by engagement of expandable wall 14 against the innerwall of service line 38 as shown in FIG. 6, the hydraulic pump 22 isturned off. This permits removal of mandrel 26 from the EFV 1 engaged inthe service line by withdrawing the fluid line from the service line.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the invention that others can, by applyingcurrent knowledge, readily modify and/or adapt for various applicationsuch specific embodiments without undue experimentation and withoutdeparting from the generic concept, and, therefore, such adaptations andmodifications should and are intended to be comprehended within themeaning and range of equivalents of the disclosed embodiment. It is tobe understood that the phraseology or terminology employed herein is forthe purpose of description and not of limitation. The means, materials,and steps for carrying out various disclosed functions may take avariety of alternative forms without departing from the invention.

Thus the expression “means to . . . ” and “means for . . . ”, or anymethod step language, as may be found in the specification and/or in theclaims below, followed by a functional statement, are intended to defineover whatever structural, physical, chemical or electrical element orstructure, or whatever method step, which may now or in the future existwhich carries out the recited function, whether or not preciselyequivalent to the embodiment or embodiments disclosed in thespecification above, i.e. other means or steps for carrying out the samefunction can be used; and it is intended that such expressions can begiven their broadest interpretation.

1. An excess flow valve (EFV) adapted to be installed in an existingservice line of a natural gas distribution system, said EFV comprising:a cylindrical housing having a first length and a second length and athrough hole therethrough for passage of gas; the EFV being engaged insaid through hole of said first length; and an expandable wall formingpart of said second length; wherein when said expandable wall isexpanded in the existing service line, the EFV is fixed and leftentirely within said service line.
 2. The excess flow valve according toclaim 1, wherein said first length and said second length are integrallyformed together as a unit.
 3. The excess flow valve according to claim1, wherein an annular wall at each end of said second length of said EFVhousing is thicker than the expandable wall between the ends of saidsecond length.
 4. The excess flow valve according to claim 3, whereinsaid expandable wall is expanded and fixed by installation equipmentengaged to said EFV after the engaged installation equipment and EFV areinserted into said service line.
 5. The excess flow valve according toclaim 4, wherein said installation equipment comprises a mandrel, fluidline and hydraulic pump which are all engaged together to deliver fluidunder pressure to said mandrel.
 6. The excess flow valve according toclaim 5, wherein said mandrel includes a cylindrical housing engaged tosaid fluid line, said mandrel housing having a pair of O-ringsrespectively fixed at opposite ends thereof and a fluid outlet holelocated between said O-rings.
 7. The excess flow valve according toclaim 6, wherein said O-rings of said mandrel are respectively fixedagainst the annular wall at each end of said second length so as to forma space between said expandable wall and said mandrel when said mandrelis engaged in said EFV.
 8. The excess flow valve according to claim 6,wherein the diameter of said EFV housing, said mandrel housing and saidfluid line are each smaller than that of said service line.
 9. Theexcess flow valve according to claim 4, wherein the engaged installationequipment and EFV are inserted into the service line through a bypasstee at an inlet side of a gas meter of said natural gas distributionsystem.
 10. The excess flow valve according to claim 6, wherein the pairof O-rings are spaced apart a distance substantially equal to thatbetween the ends of said second length.
 11. An excess flow valve (EFV)adapted to be installed in an existing service line of a natural gasdistribution system, said EFV comprising: a cylindrical housing having afirst length and a second length and a through hole therethrough forpassage of gas; the EFV being engaged in said through hole of said firstlength; and an expandable wall forming part of said second length;wherein said expandable wall can be expanded and fixed in said serviceline; wherein an annular wall at each end of said second length of saidEFV housing is thicker than the expandable wall between the ends of saidsecond length, and wherein said expandable wall is expanded and fixed byinstallation equipment engaged to said EFV after the engagedinstallation equipment and EFV are inserted into said service line. 12.The excess flow valve according to claim 11, wherein said first lengthand said second length are integrally formed together as a unit.
 13. Theexcess flow valve according to claim 11, wherein said installationequipment comprises a mandrel, fluid line and hydraulic pump which areall engaged together to deliver fluid under pressure to said mandrel.14. The excess flow valve according to claim 13, wherein said mandrelincludes a cylindrical housing engaged to said fluid line, said mandrelhousing having a pair of O-rings respectively fixed at opposite endsthereof and a fluid outlet hole located between said O-rings.
 15. Theexcess flow valve according to claim 13, wherein said O-rings of saidmandrel are respectively fixed against the annular wall at each end ofsaid second length so as to form a space between said expandable walland said mandrel when said mandrel is engaged in said EFV.
 16. Theexcess flow valve according to claim 13, wherein the diameter of saidEFV housing, said mandrel housing and said fluid line are each smallerthan that of said service line.
 17. The excess flow valve according toclaim 11, wherein the engaged installation equipment and EFV areinserted into the service line through a bypass tee at an inlet side ofa gas meter of said natural gas distribution system.
 18. The excess flowvalve according to claim 13, wherein the pair of O-rings are spacedapart a distance substantially equal to that between the ends of saidsecond length.
 19. An excess flow valve (EFV) adapted to be installed inan existing service line of a natural gas distribution system, said EFVcomprising: a metallic cylindrical housing having a first length and asecond length and a through hole therethrough for passage of gas; theEFV being engaged in said through hole of said first length; and anexpandable wall forming part of said second length; wherein saidexpandable wall can be expanded and fixed in said service line; andwherein an annular wall at each end of said second length of said EFVhousing is thicker than the expandable wall between the ends of saidsecond length.
 20. An excess flow valve (EFV) adapted to be installed inan existing service line of a natural gas distribution system, said EFVcomprising: a cylindrical housing having a first length and a secondlength and a through hole therethrough for passage of gas; the EFV beingengaged in said through hole of said first length; and an expandablewall forming part of said second length; wherein when said expandablewall is expanded in the existing service line, the EFV is fixed and leftentirely within said service line; and wherein said expandable wall isexpanded and fixed by installation equipment engaged to said EFV afterthe engaged installation equipment and EFV are inserted into saidservice line.
 21. An excess flow valve (EFV) adapted to be installed inan existing service line of a natural gas distribution system, said EFVcomprising: a cylindrical housing having a first length and a secondlength and a through hole for passage of gas therethrough; the EFV beingengaged in said through hole of said first length; and an expandablewall forming part of said second length; wherein said expandable wall isformed of metal and is capable of and adapted to be permanently fixed inthe service line by internal application of pressure.
 22. An excess flowvalve (EFV) fixed in place within an inner wall of an existing serviceline of a natural gas distribution system, said EFV comprising: acylindrical housing having a first length and a second length and athrough hole therethrough for passage of gas; the EFV being engaged insaid through hole of said first length; and an expanded wall of saidcylindrical housing forming part of said second length and retained infixed frictional contact against the inner wall of said service line,said expanded wall having been expanded outwardly by internal pressure.23. A method for installing an excess flow valve in an existing serviceline of a natural gas distribution system, wherein the excess flow valvehas a passageway for passage of gas therethrough, the excess flow valvebeing engaged in a through hole of a first length of a cylindricalhousing, and the cylindrical housing having an expandable wall forming apart of a second length thereof, the expandable wall of the housingbeing capable of being expanded and fixed within the service line, themethod comprising: extending the cylindrical housing with the excessflow valve therewithin into the service line of the natural gasdistribution system serving an existing structure; and causing theexpandable wall forming part of the second length of the cylindricalhousing to expand outwardly by application of internal pressure so as tofirmly frictionally engage the interior wall of the service line so asto fix and leave the EFV in the service line.
 24. The method of claim23, wherein the expandable wall of the second length of the cylindricalhousing is caused to expand by delivering fluid under pressure thereto.25. The method of claim 23, wherein the cylindrical housing with theexcess flow valve therewithin is forced to a position within the serviceline by use of a mandrel.
 26. A method according to one of claims 23through 25, wherein the location in the service line into which thecylindrical housing with the excess flow valve therein is delivered isunderground.
 27. The method of claim 23, wherein the service line has abend therein and the cylindrical housing with the excess flow valvetherewithin is forced around the bend and downstream therefrom to thelocation at which the expansion takes place.